在UnderscoreJs中获取数组中数字之间的对象

Question

I'm looking for a way in Underscore.js to find two numbers that lay between a number in an array.

Number cannot be < 5 && > 20 or any of the numbers in the list.

I have a working Javascript version

 var data = [ { key: 5 }, { key: 10 }, { key: 15 }, { key: 20 } ]; function getBetween(xTest, xyLists) { for (var ic = 0; ic < xyLists.length - 1; ic++) { if (xyLists[ic].key <= xTest && xyLists[ic + 1].key >= xTest) return [xyLists[ic], xyLists[ic + 1]]; }; } console.log(getBetween(9, data)); //expect 5,10 console.log(getBetween(16, data)); //expect 15,20 

I have been trying something like this

 _.first(_.filter(xyLists, 
   function (item) { return item.key >= xTest; }), 2);

Answer 1

If the array is already sorted by the key value, then you need to compare the previous or the next value also like

 var data = [{ key: 5 }, { key: 10 }, { key: 15 }, { key: 20 }]; function getBetween(xTest, xyLists) { return _.map(_.filter(xyLists, (item, idx, arr) => (item.key <= xTest && (arr[idx + 1] || {}).key >= xTest) || (item.key >= xTest && (arr[idx - 1] || {}).key <= xTest)), item => item.key) //return xyLists.filter((item, idx, arr) => (item.key <= xTest && (arr[idx + 1] || {}).key >= xTest) || (item.key >= xTest && (arr[idx - 1] || {}).key <= xTest)).map(item => item.key) } snippet.log(JSON.stringify(getBetween(9, data))); //expect 5,10 snippet.log(JSON.stringify(getBetween(16, data))); //expect 15,20 

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